Free Oscillations of the Earth



The study of the earth's free oscillations has been an extraordinarily productive area of research in geophysics for the past 25 years. After every large earthquake since the Chilean event of 1960, seismometers, gravimeters, and strain gauges have supplied seismologists with several days o f data containing the eigenperiods of a wide variety of different normal modes. Theoreticians have responded with elegant theories and computational procedures that have verified the observations to remarkable precision and attested to the fact the earth is an almost perfectly elastic, spherically symmetric, and simply layered body.